PS-C04-7: REPRODUCIBILITY OF CAROTID TONOMETER AND FEMORAL CUFF-BASED PULSE WAVE VELOCITY: INTERACTION WITH OPERATOR SKILL

Abstract

Objective: Large artery stiffness is strongly correlated with cardiovascular outcomes. The stiffness of the artery can be measured non-invasively using carotid-femoral pulse wave velocity (cfPWV). Originally cfPWV assessment was performed by ECG-gated applanation tonometry at the carotid and femoral site. High quality applanation tonometry is a learned skill. To increase ease of use, many commercial devices now use a pneumatic cuff for femoral pulse acquisition but still retain tonometry-based carotid pulse acquisition. Lack of clinical uptake of cfPWV may be due to perceived poor repeatability, especially where a learned skill is required. This study aimed to quantify how many measurements a skilled and unskilled operator are required to take to obtain an acceptable cfPWV measurement. Design and method: Supine cfPWV measurements (SphygmoCor XCEL, AtCor, Sydney) was measured in healthy participants (n = 15, age 30 ± 15 years, 12 female) by both an inexperienced and experienced operator 10 times in each participant. True cfPWV was taken as the average of twenty cfPWV measurements (regression to the mean). The time required to perform the cfPWV assessment by an experienced operator was additionally recorded in a separate set of participants referred to the clinic. Data analysis was performed using regression analysis and Bland-Altman plots. Results: The first cfPWV measurement made by both operators (experienced and inexperienced) resided within ± 0.36 m/s (cut off for a 10% increased risk of cardiovascular events) of the true cfPWV in 87% (n = 13) of individuals. The average of the first two cfPWV measurements fell within ± 0.36 m/s of true cfPWV for all participants for the experienced operator and 93% of participants for the inexperienced operator (Figure). Distance measurements were not significantly different between operators (p = 0.14). The total time required to perform a full cfPWV assessment (one distance measurement and two cfPWV measurements), on average, was 238 ± 79 seconds (3 minutes and 58 seconds). Conclusion: Irrespective of operator experience an accurate measurement of cfPWV can be obtained by averaging two measurements. These results suggest that cfPWV measurement error should not necessarily be a contributing factor to the limited clinical uptake of cfPWV. The measurement does take considerable time, and this may be a barrier of uptake, along with perceived clinical applicability of arterial stiffness measurement.